Cathode for the electrolytic refing of metals



Sept. 25 `1923. 1,468,838

c. H. SCHUH CATHODE FOR THE ELEGTROLYTIC REFININGOF METALS Filed Sept. 22 1922 9 f 70 jij' 3f /0 7 5,

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PatentedV Sept. 25, 1923;

CHARLES H. SCHUH, F BROOKLYN, 'NEW YORK.

oAT'HoDEroR THE ELECTROLYTIG REFINING or METALS. i i

Appncann 1aed september 22, 1922. serial no. 589,945.

1/ o YZ whom 'it may concern:

Re it known that I, CHAN-.as H. SCHUH, a citizen of the United States, and a resident of' the borough of Brooklyn, city of New York, State of New York, have invented a new and useful Improvement in Cathodes which the following is a specification, containing a full detailed explanation of the principle ofthe invention, and the best manner in which lhave' contemplated its application, all worded so as to, enable those skilled in the art to which it appertains to make and use the'same. ai.

illy invention relates to an improvement in the clectrolytic refining of metals.

t is particularly useful in the refining'of copper from its ores and other sources of the crude metal by the aidofthe electric current. l Y -v It is especially concerned with the formal tion of a uniform coating -of copper, on the so-called cathode blanks used in making what are commonly known as cathode start-- ing sheets, and it affords simultaneously an easy,y effective and economical method of -deposited electrolytically, possesses the tend-l ency to adherermly to the metallic cathode.v

stripping or removing these sheets from the cathode blankson which they are formed.

In the process of refining metals from their ores, mattes and other sources of supply, it is customary to manufacture first thin starting sheets by the electrolysis of suitable salts of-the'metal, the' metal being dissolved awa from the impure anode and being deposit-ed inthe form of-a coating on the metallic cathode; The removal of this coat`- ing, after it has attained the proper thickness, usually one-eighth of anv inch, is fraught with considerable difficulty, dueto the fact that the copper film or coating.

Various means have been devised for the counteraction of this difficulty, such as. the application of a coating of grease, oil, or fat` either mixed or unmixed with graphite, either natural or artificial, and fof other .similar materials, conducting the electric.

current, or the simple application of a topcoat of graphite or similar material on the oil under-coat. This method of alleviatlng the difiiculty of removing cathode starting sheets from the blanks on which-they are formed. is not very effective, for the coating must be 'applied after each and every time thatthestarting sheets are stripped;

it entailsxconsiderable labor, loss of time in i the process, and it is likewise uneconomical,

due to the continuous replacement of the oiland graphite'lms..

I am also familiar with the method of .grooving theedges of the cathode blanks -a methodA which is perhaps" most widely used at presentso that the starting' sheets can be easily separated from the former along the line of the groove. However. when this process is used, a strip of copper is obtained from the three edges of the cathode i blank, which must be sent back to the refining or melting furnace for remelting,

entailingl a considerable Waste of the metal. Furthermore, it often happens that the start'- ing sheets are spoiled when being stripped ofi" the cathodes in this manner, as they are liable to be torn and otherwise injured. This method has' been found to be unecconomical, resulting in the loss of time, and involving onsiderable labor in theremoval of the edge strips and their further treatment in the refining process. M

Similarly; l am entirely congnizant of No. 1,l63',337, in which it .is shown that a wedge-shaped groove is cut out in the three peripheral edges. of the cathode blanks This Icut is filled with plastic materials which act as non-conductors, or it may be merely left open or void. Such a method is productive 'of many disadvantages, among which` may be mentioned the difficulty of making so small a groove in the peripheral edges of the cathode blanks and of filling the same-.With plastic materials, the irregu the art disclosed in United States-Patent` overlaps the sharp edges and even fills the inside edges' of ,the Wedge-shaped or V" shaped groove, bridgingthe gap.

Other methods of' facilitating the removal of the cathode starting sheets, such as per@ forating the edges' and filling the perforations-With non-conductive, plastic compositions, cutting grooves on both sides of the.

plates and filling the same in similar manv film of plated metal, Without the need of using oil or grease coatingsover the surfacev of the cathode. The surface of the aluminum cathode coversl over rapidly With a thin invisible film of oxide, which prevents the plated metal from adhering firmly to the cathode. As vfar asis known,4 this property of aluminum has not been applied to; the electrolytic refiningof` metals on an industrial scale, and particularly to `the electrolytic refiningof copper. My. invention uses optionallyandA preferably aluminum metal for the cathode, and consists fof a special lform of such cathode which renders it possible toV obtain these and other advantageous eects, which have not been possible up to the .present time in this art.

vThe objectof my invention is to provide an easy, economical, effective and simple means of removing cathode starting sheets from the cathode blanks on which they are formed.

A further object of my invention is to secure a uniform coating of the metal, of even thickness throughout While simultaneously effecting the stripping of the sheets of metal from the cathode blanks Afurther object of my invention is to avoid the loss in time, the additional cost 'of labor and materials, and the deficiency in the quality of the starting sheets 'as 'they are made by former process. In my process of preparing, and using cathode blanks it is not'necessary to use grease or `oil compositions, although. I do not limit myself merely to the use ofnietallic cathodes which allow this advantage to be gained.

A further object of my` invention is to sc cure a cathode blank from which the starting sheet may be easily stripped and which does not have to be removed from. the supporting frame-Work, Which holds it, either before, during or after the stripping process. `My invention accordingly affords a per- I marient cathode blank A further object ofmy invention is yto make starting sheets, which 'are provided With hanging strips, so that these starting l sheets may be veasily attached to the crossbars, running across the electrolytic cells. vA further object of my invention is to avoid waste of metal, which occurs when using the common forms of cathode blanks both in the removal of the cathode starting sheets therefrom, and in the fastening of the latter to the cross-bars on the electrolytic cells.

Myinvention may be applied With good results to the electrolytic refining of all metals and in particular to the electrolytic refining of copper from its ores and other sources of supply.

The drawing illustrates by Way of ex-m ample, one Way of carrying out this invention, as follows: Figure l represents a cathode blank in elevation.

Figure 2 representsa blank.

. Figure 3 represents an ,elevation/of the frame in Whichthe cathode blank fits.

Figure 4 represents a plan view of said frame.

Figure 5 represents an `assembled cathode form as 'used in the cell.

Figure 6 represents a plan view ofthe top piece.

' Figure 7 represents a section on the line plan View of such '7-7 of` Figure 5.

l best adapted-for'my purpose.

Figure l represents the cathode blank in the form in which it, is made to suit my purpose.I 8 is the main body of the, cathode. 9 are the cut-out strips, which enable `the cathode to wbe conveniently vsupended from the cross-bars von the electrolytic cells. 10

represents a beveled edge, made at an angle I of 45 degrees, and extending around 'the ico three4 sides ofthe cathode blank and like- Wise the cutout top of the blanks Withthe exception of the' three top-most edges, as may be clearly seen in the diagram. 11Nw ll-ll are the perforations in the-cutout strips for fastening.- the cathodeblanks to the cross-bar of the electrolytic cell. Thev thickness of the sheet' is optional, and it can be made as thin as may be desired.

would prefer a thickness of 3/40ths of anv inch. The Width of the bevel is equal to the thickness of themetal. l/Vhile-I have i'ndicated three cut-out strips at the top of the cathode, as being suiic-ientv to support the Weight of the metal, nevertheless, any numbilr of strips or lugs may be used as desirl a e.

'I prefer to makel my cathodev blank from aluminum metal or aluminum alloy or brass, for` then I do not have to `use any grease or and other` metals, whereupon it may eoome necessary to use the usual grease and graphite compositions I wish to call'special attention to a parl ticular feature of my invention, namely the beveled edge. This form of edge allows me to secure a lirm connection between the cathode blanks and the supporting frames, 'was I will disclose in full detail later in these specifications. IIt also allows me to obtain simultaneously a lm of metal of even thickness throughout, which cannot be accomplished by any, of the forms of cathode blanks, specially shaped for an easy and effective removal of the cathode starting sheets, that are known vupto the present time. Those familiar with the art of eleclytic refining ofl metals may know that a decrease in the thickness of the cathode re-' sults in the formation of increased thicknesses of metal lat those spots where the cathode is, thinner than elsewhere. While I prefer to cut a beveled edge in my cathode blank for the purpose of securing a good joint Abetween it and the Asupporting frame work, nevertheless I protect this decreased thickness of meta in the cathode blank in a maner 'that I will Adisclose inA full de-- tail. later in the patent specifications. Furthermore, while the. cathode possesses sharp edges, the well-known disadvantage of such construction, namely, the formation of thick knobular deposits of copper around these sharp points and edges, is 'avoided through the protection afforded by the sup'- porting frame-work. At the same time, all the structuraladvantages of this angular construction are made available.

Figure 2 is the top view of the aluminum or other metal cathode blank The beveled Figure 3 is a side view ot' thesupporting frame-work` which is used to hold the .cathode starting sheets. Thisframe-work is made 'of' any material, resistant to acid solutions` a non-conducto'r of electricity possessing rigidity and capable of being machined to exact form and size' and-of retaining its dimensions, even when made in a very thin sheet( I use hard .rubber preferably.v for this purpose, for it not only possesses the aforementionedproperties, but it is also cheap. easy to work and shapeto the desired form, very. resistant to' acids and acid solutions and non-warping. here may also be used foi' the supporting frame-work` such materials as phenol-formaldehyde condeusation products, vulcanized liber board, various treated wood compositions, which may b e covered with acid-resistant paint or varnish, and other similar substances and compositions, which do not conduct the-electricicurrenti .As has been stated, I prefer to `use hard rubber :tor this purpose, but 'I' do not limit myself solely to the use of such material, there being many other natural and manufactured products which can serve for the same purpose.

The frame is made in the'form of avery thin web, substantially about one tenth of an inch, but any .desirable thicknessmay be used inaccordance with the conditions.. The -web is designated by 14 in Figure 3,

and is provided with a thicker edge 13, about one quarter of an inch thick, around three of its edges, as is clearly visible from the figure. This-edge is provided with a double bevel, so that one cathode blank may be inserted on either side of the web.

The manner of` making this supporting frame-work a-nd the beveled edge iS seen further from Figure t, which is a top View of the construction. The edge l3fis shown provided with the 45 degree bevel l5. This bevel is made vaccurately to dimensions, so that the beveled cathode blanks fit tightly within the-iframe. This vis an important feature of t-he invention, as a tight-fitting beveledrcdge 'means that no deposit of copper can. be formed under the sharp edge ofv the`bevcled aluminum cathode. fords a tight It also afjoint between the rubber frame-work and the aluminum cathodes,

so that the former is held fast to the latter and supported thereby. This eliminates the necessity of furnishing separate supports for the rubber frame-work, as the aluminum catlioclcs are themselves supported by means of the top cut-out strips, which are riveted' to the cross-bar Vof tl``e 'electrolytic cells. The rubber frame-work then hangs from the aluminum cathodes, and while it supports them and protects them, the aluminum cathodes nevertheless alsoact as supports for rubber frame-work. In order to make this joint between the rubber frame-work and the aluminum cathodes more secure, a rubber cement of the type that may be bought on the market for gluing rubber to metal, may Aalso be used. Furthermore, the tight-fitting beveled edge of the rubber frame-work protects the decreased thickness of metal in the aluminum cathode. This is likewise an important feature of ythe invention, for if the decreased thickness of metal is left exposed, and copper or other metal is deposited thereon, the deposit becomes knobular, irregular, thicker than the rest of the sheet of metal and also full of air and gasholes. This is .avoided by my invention, as every care is taken to protect decreased thicknesses of metal in the cathode, conscquently, all sharp edges and corners, through the medium of the encompassing hard rubber framework.

Figure 5 is a sideview of the entire ,as-

-vsembled cathode Ablank,'as I prefer to have of the cathode blank individual,

lifrure lrrefers to a to -nece made ot the frame-Work.

same material as the rest of the supporting' This is placed right on top ot' the main piece of the rubber frame-work. It fits flush at the edge 17 and is provided ,with a beveled part 18, which tits accurately over the bevel l of the aluminum cathode.

The rubber top-piece is made with three e cut-out sections, as may be clearly seen from the top view in Figure y(3, so that the metal of the cut-out strips, 9, of the-aluminu1n vcathode is lett bare. while the intervening spaces are filled with the materiall of the top-piece. Hence, the metal deposits electrolytically on these cut-out strips 9, giving Vla. starting` sheet vwith corresponding strips' on both sides of the cathode.

. or lugs for easy fastening to the cross-bars of the electrolytic cells, in the further stages of the` refining process. It .fis pointed out again that this rubber top-piece aiords protection for all `decreased thicknesses in vt-he metal of the cathode. so as to avoid any ir-.

' regular deposits of the metal being 'formed thereon. A v

Figure. is section through the composite cathode blank on the line 7-7. The

aluminum cat-bodes are seen at 8, the web of the rubberl -trame-work at 14, therubber top-piece at 16, the tight fitting beveledr edges at 18. thecut-out strips ot the alumi-A- num cathodes at 9 and the cross-bar ot the elcctrolytic cell at 19. y

As seen from the above` description, my inyention affords an important improvement in the art ot making cathode blanks and stripping cathode starting sheets in the electrolytic refining ot metals. Ihave described a preferred method of'makingitliese cathode blanksi'but'I do not limit myself to this solemode of carrying out the invention. It is possible to construct the-cathode. so that one sheet of metal only'is used and the metal. being refined. may be deposited In this case the rubber frame-work consists merely of an edge. running around the three sides of the metallic cathode and ot the two or more cutout strips at the top. The ends -ot these strips, may' be fastened to the" cross-bar ot` the electrolytic cells, but this is not necessary as the joint between the metal cathode and lthe rubber end strips may be made tight enough and strong enough by the -use of special rubber cements to avoid such additional support. ,In this case the peripheral edge of the metallic cathode is cut out in the shape ofga V, with the apex of the V pointing outwards or downwards. `The rub.

In the latter case it may be necessary tol use the usual type of grease and oil c0mpos1= tions to smeanover the surface of the metal so as to prevent too `tight adherence of the deposited metal thereon.

In thee-ourse of my experimentation with the types of cathodes described above, I have also remarked that it is Well to make them equally as largeor slightly larger but nov smaller than the anode. It this is, not done, that is, if the cathode is made smaller than thel anode, then there is danger of the formation of irregular deposits of the relined metal on the cathode.-`

My invention may be applied to the electrolytic refining ofall metals,'but it has special advantages in the electrolytic refnin ot copper. IVhile it is primarily intende for such purpose, I expressly state that I do not limit myself to this one field of its application. I have found thatA new, novel and important eects in the electrolytic refining of metals'Lcan q:be gained by the use of my invention, which I have disclosed in full detail in a preferred'mode of application, but in applying for this patent I wish to, call attention to the fact that the principles involved therein, the use of aluminum metal or other suitable metals, theformation of an edge to assist in the stripping of the-.cle- I posited metal, the protection of this edge to avoid irregular deposits on the cathode, the

size of the cathode with reference to the size of the anode, are the important featureso'f the invention and not the particular mode in which it is carriedout.

The termilm-forming metals is used in the claims to cover such metals as aluminum, 1

aluminum alloys. brass or their equivalents,

which are considered to Vowe their property ot toi-mation ot easily strippvable electrolytic' The terms chamfered and tapering` away are used in the claims to' refer tol an edge whichma'y be beveled, concave, convex,.

etc.,in order to be fitted for use in the disclosedstructure.

principles and construction of my invention,

-The termFcathode form is used to include a cathode or cathode blankor equivalent structure.-

Having thus described in full detail the I seek to claim as follows:

. 1. A cathode comprising a plate having a chamfered edge, said plate adapted to fit a non-conducting frame therefor, said plate comprising a film-forming metal.

2. A cathode comprising a plate having an edge tapering away from its frontl face towards its rear face, said plate adapted to fit a non-conducting frame therefor, said platev comprising a film-forming metal.

3. In an electrolytic cell, a cathode having' an area as large atleast as the area of the anode.

4. In an electroiyticy cell for the refining of copper, a cathode having an effective area as large at least as the area of the anode.

5. A cathode comprising a plate having a chamfered edge, said plate adapted to fit a non-conducting frame therefor.

6. A cathode comprising a plate having an edge tapering away from its front face towards its rear face, said plate adapted to fit a non-conducting frame therefor.

non-conducting framework carried by said p late to prevent exposure of the chamfered e ge. v A 10. A cathode form comprising in combination a plate the upper portion of which is cut away to form suspending members the peripheral edges of the plate and the suspending members being beveled.l

11. A cathode form comprising in combination a plate having a portion of its upper body cut away to form suspending members. the edges of the plate vand the suspending members being chamfered. a framework adjacent said plate to prevent exposure of the having its edges tapered to provide an outwardly directed V-sbaped edge adapted to `fit a non-conducting frame therefor.

13. `A cathode form comprising in combination, a` plate having its edges beveled to provide an outwardly directed V-shaped edge, and means adjacent such edge to pre vent its exposure to the action of an electrolytic solution when submerged or immersed therein` 14. A cathode form as set forth in claim 13, in which the means'for preventing exposure of the edge comprises a framework having an inwardly directed V-shaped surface adapted to it snugly against the edge of the plate.

15. In a cell for the electrolytic refining of copper, a cathode form comprising an aluminum platehaving its edge tapering from its front face toward its rear face, the eHective larea of the plate being as large, at least, as the area of the anode.

16. A cathode form comprising in combi nation, a greasy metal plate having a beveled edge, said plate being cut away in its upper body portion to provide suspending members, the edges of the suspending members being beveled` a hard rubber framework adjacent the plate and beveled to it snugly against the edge of the plate. and a hardrubber top-piece having a beveled surface to enable it to fit snugly against the edges of the suspending members. v

17 In an electrolytic cell' for the refining of copper, a cathode form' comprising an aluminum plate having a portion of its body cut away to provide suspension members, the

edges of the plate and suspension members f tapering from the front face towards the rear face of the plate, a hard rubber framework adjacent said plate beveled to t snugly against the edge of the plate without diminishing the area of the front face of the plate, and a hard rubber top-piece adjacent the suspension members beveled to fit snugly against the edges of the suspension members without diminishing the exposed surface of thevfront face of those members, said cathode form having an effective surface as large, at least, as the effective surface of the plate.

18. A cathode form comprising ametallic plate and a framework adjacent said plate to prevent access of the solution of an electrolvtic cell to the edges of the plate without diminishing the surfa ce of the front face of the plate, when said plate is' used in an electrolytic cell.

19. A cathode form comprising in combination a plate having a chamfered edge and a framework carried by said plate, said framework being Hush with the effective depositin g surface 

